1. Field of the Invention
The present invention relates to a method for manufacturing nanoparticles using a chemical vapor condensation process, and more particularly, to a method for manufacturing metal oxide hollow nanoparticles with excellent properties more easily and simply by a vapor synthesis process employing metal β-diketonate as a precursor, and metal oxide hollow nanoparticles manufactured by the method.
2. Description of the Related Art
Conventional metal oxide hollow particles originated from metal oxide or polymers are mainly applied to carriers of drugs, cosmetics, inks and so on and catalysts. Despite of this wide range of the applications, it is difficult to improve properties of the conventional metal oxide hollow particles because: sizes of the metal oxide hollow particles as manufactured are greater than several hundreds of nanometers; and using conventional synthesis methods, it is difficult to change various functional characteristics that are generally obtained by decreasing the metal oxide hollow particles to the size of less than 100 nm.
The mechanism for forming hollow particles largely relies on the conventional synthesis process. Examples of the conventional synthesis process are: a sol-gel process, which is a liquid phase synthesis method, a spray pyrolysis process, which is a gas phase synthesis method, and a spray drying process.
However, the above processes may cause a change in the microstructure of particles. In the case of the sol-gel process, a heat treatment for removing polymer core particles or interstitial organic materials is accompanied to form hollow structure. During the heat treatment, agglomeration of the particles and particle growth occur due to thermal coagulation of the particles. As a result, it may be difficult to manufacture hollow nanoparticles of less than 100 nm.
In consideration of the particle growth by the heat treatment, numerous studies have been actively continued to form a hollow structure through coating polymer core particles with sizes of several tens of nanometers. However, it may be very difficult to form a coating layer uniformly on the surface of each core particle with the size of less than several tens of nanometers. Therefore, successful synthesis of hollow nanoparticles with sizes of less than 100 nm has not been yet reported.
In the case of the gas phase synthesis processes such as spray pyrolysis process and spray drying process, a nozzle generates droplets of a precursor and, droplet sizes are in several microns. Hence, it may be difficult to manufacture hollow nanoparticles with sizes of less than 100 nm.